1. Field of the Invention
This invention relates to disused radiological sources, and more specifically, this invention relates to a system and method for packaging disused radiological sources for dry storage, transportation and disposal.
2. Background of the Invention
There are several types of packaging for radioactive material, depending on the activity of radioactive content. Per Title 10 of the Code of Federal Regulations (CFR), Part 71 entitled “Packaging and Transportation of Radioactive Materials,” a Type B packaging is required for transportation of radioactive material of Type B quantities. (Type B quantity means a quantity of radioactive material greater than a Type A quantity.)
Packaging means the assembly of components necessary to ensure compliance with the packaging requirements of 10 CFR Part 71. It may consist of one or more receptacles, absorbent materials, spacing structures, thermal insulation, radiation shielding, and devices for cooling or absorbing mechanical shocks. The vehicle, tie-down system, and auxiliary equipment may be designated as part of the packaging.
After discharging from reactors, commercial spent nuclear fuel (SNF) in the U.S. is typically stored in spent fuel pools at the reactor sites for over five years. Then it is moved into dry cask storage systems (DCSS) at a licensed Independent Spent Fuel Storage Installations (ISFSI) for up to 40 years. The license of ISFSI may be renewed for an additional term not to exceed another 40 years per 10 CFR 72.42. Typical DCSSs weigh over 100 tons.
Each dry storage canister/cask could contain multiple tens of SNF assemblies, wherein the canisters are placed in overpacks that are designed for long term storage but not transportation after storage or disposal. (An overpack, as defined by the International Air Transport Association's Dangerous Goods Regulations, is an enclosure used by a single shipper to contain one or more packages and to form one handling unit for convenience of handling and storage.)
There are many other forms of SNF and high level waste (HLW) at Department of Energy (DOE) sites and facilities, and disused radiological sources that need to be moved out of their current storage pools for extended dry storage, subsequent transportation, and final disposal at geological repositories. For example, sealed capsules of cesium and strontium isotopes heretofore were used to irradiate food for preservation and sterilize medical equipment. Approximately 1900 of these capsules exist.
Department of Energy (DOE) facilities are not designed for wet-to-dry storage of disused radiological sources using commercial SNF DCSSs.
DOE has planned to dispose all HLW and SNF, regardless of commercial, defense, or research origin, in a common mined geologic repository. Separate mined repositories for DOE SNF and HLW as well as deep borehole disposal options have been proposed, particularly for small waste forms such as Cs/Sr capsules. Currently, these capsules are stored in pool cells at Hanford's Waste Encapsulation and Storage Facility (WESF).
A need exists in the art for a system and method to enable one time packaging of disused radiological sources to facilitate transfer, storage and transportation and disposal. The system and method should not require unusual materials or material handling protocols. Also, the system and method should facilitate storage and disposal in current and proposed repository paradigms.